Compact portable oxygen concentrator

ABSTRACT

A compressor assembly for a portable oxygen concentrator includes a first compressor chamber having a first connector, a second compressor chamber having a second connector, and a tube having a first end having a first connection interface configured to connect to the first connector and a second end having a second connection interface configured to connect to the second connector. The first connection interface is shaped to maintain the connection between the first connector and the first connection interface in a fixed orientation and the second connection interface is shaped to maintain the connection between the second connector and the second connection interface in a fixed orientation. One or more of the first connector, the second connector, and the tube are compliant.

INCORPORATION BY REFERENCE TO ANY PRIORITY APPLICATIONS

Any and all applications for which a foreign or domestic priority claimis identified in the Application Data Sheet as filed with the presentapplication are hereby incorporated by reference under 37 CFR 1.57. Thepresent application claims priority benefit of U.S. ProvisionalApplication No. 62/827,689, entitled “COMPACT PORTABLE OXYGENCONCENTRATOR,” filed Apr. 1, 2019, which is incorporated herein byreference in its entirety.

BACKGROUND Field

The present disclosure relates to oxygen concentrators for personal useand in particular to portable oxygen concentrators.

Description of the Related Art

Personal oxygen concentrators are devices that convert ambient air to anoxygen enriched gas for therapeutic use. They are becoming increasinglypopular as alternatives to liquid oxygen vessels and compressed gascylinders. Such personal oxygen concentrators exist in both portableform for ambulatory use and stationary form for use inside the home. Tobe practical for everyday use by patients needing therapeutic oxygen,portable oxygen concentrators are generally preferred over stationaryones. It is desirable that such portable oxygen concentrators be small,lightweight, efficient, reliable, and relatively inexpensive. Efforts todesign an oxygen concentrator having all of these desirable attributesmay be inherently limited by the size and weight of the individualcomponents. Further reductions in size and weight of portable oxygenconcentrators without sacrificing performance may require new approachesto concentrator design.

SUMMARY

Portable oxygen concentrator elements may be provided that includeimproved compressor control features, high density gas tightinterconnects, integrated sensor blocks, space efficient adsorberdesigns, improved airflow, and improved battery retention. The result ofthe elements is an extremely compact, light reliable portable oxygenconcentrator that is easy to assemble and relatively inexpensive.

In one aspect, a battery retaining system for a portable oxygenconcentrator is provided. The battery retaining system includes a firstrail configured to receive a first slide of a battery, a second railconfigured to receive a second slide of the battery, the second railbeing spaced apart from the first rail so as to form a channelconfigured to receive the battery, and a flexible stiffening mechanismconfigured to impart a biasing force on a surface of the battery whenthe battery is received within the channel. The flexible stiffeningmechanism includes a protrusion projecting from the first rail at leastpartially towards the second rail and a slit positioned behind theprotrusion and configured to facilitate travel of the protrusion foreand aft.

In some embodiments, the system further includes one or more protrusionsprojecting from the second rail at least partially towards the firstrail, the one or more protrusions being configured to contact thebattery when the battery is positioned within the channel. In someembodiments, the channel extends between an open proximal end and aclosed distal end, wherein at least one of the one or more protrusionsprojecting from the second rail are positioned proximally relative tothe protrusion of the first rail. In some embodiments, the channelextends between an open proximal end and a closed distal end, wherein atleast one of the one or more protrusions projecting from the second railare positioned distally relative to the protrusion of the first rail. Insome embodiments, the one or more protrusions projecting from the secondrail comprise a first protrusion positioned proximally relative to theprotrusion of the first rail and a second protrusion positioned distallyrelative to the protrusion of the first rail. In some embodiments, theflexible stiffening mechanism maintains contact between the first railand the battery to stabilize the battery within the channel, the batteryhaving a battery size that is smaller than an upper tolerance level. Insome embodiments, the flexible stiffening is configured to impart thebiasing force on the surface of the battery so as to align an electricalconnector of the battery with an electrical connector of the portableoxygen concentrator. In some embodiments, the flexible stiffeningmechanism is configured to impart the biasing force on the surface ofthe battery to impart stability to the installation of the battery. Insome embodiments, the biasing force of the flexible stiffening mechanismis sufficiently flexible to permit translation of the battery within thechannel past the protrusion.

In another aspect, a portable oxygen concentrator is provided. Theportable oxygen concentrator includes a chassis base, a printed circuitboard mounted at a superior end of the chassis base, the printed circuitboard including a first electrical connector, and an outer housingconfigured to removably couple to the chassis base. The outer housingincludes one or more controls of a user interface and a secondelectrical connector in electrical communication with the controls ofthe user interface, the second electrical connector being positioned toalign with and mate with the first electrical connector when the outerhousing is coupled to the chassis base.

In some embodiments, the printed circuit board comprises a userinterface display. In some embodiments, the outer housing is configuredto define an enclosed volume around the printed circuit board whencoupled to the chassis base. In some embodiments, the outer housing isconfigured to seal the enclosed printed circuit board from externalmoisture when coupled to the chassis base. In some embodiments, thefirst electrical connector is oriented on the printed circuit board soas to face in a generally superior direction and the second electricalconnector is oriented on the outer housing so as to face in a generallyinferior direction.

In another aspect, a gas concentrator is provided. The gas concentratorincludes a chassis base, a compressor assembly, an outer housing coupledto the chassis base so as to define an internal volume enclosing thecompressor assembly, and a shell structure positioned within theinternal volume, the shell structure including one or more insulatingpanels disposed about the compressor assembly.

In some embodiments, the shell structure separates the compressorassembly from one or more elements positioned within the internal volumeof the concentrator, the one or more elements comprising one or moreadsorbers coupled to the chassis base, one or more pneumatic modules,one or more electronic modules, or one or more sensor modules. In someembodiments, the shell structure forms at least a portion of an at leastpartially sealed chamber around the compressor assembly. In someembodiments, the gas concentrator further includes a printed circuitboard, the printed circuit board forming at least a portion of the atleast partially sealed chamber. In some embodiments, an interior surfaceof the outer housing forms at least a portion of the at least partiallysealed chamber.

In another aspect, a gas concentrator is provided. The gas concentratorincludes a chassis base, a compressor assembly, an airflow generator,one or more exhaust ports, and an outer housing coupled to the chassisbase so as to define an internal volume enclosing the compressorassembly and the airflow generator, the outer housing including one ormore air inlets, wherein the one or more air inlets are recessed withinthe outer housing or extend along a curved or angled surface of theouter housing, wherein the airflow generator is configured to directairflow along an airflow path between the one or more air inlets and theone or more exhaust ports.

In some embodiments, the one or more air inlets include a first airinlet and a second air inlet, wherein the first air inlet and the secondair inlet are positioned on opposite surfaces of the housing. In someembodiments, the one or more exhaust ports comprise a first exhaust portand a second exhaust port, wherein the first exhaust port and the secondexhaust port are formed within opposite side surfaces of the chassisbase. In some embodiments, the gas concentrator further includes abattery coupled to the chassis base, wherein the one or more exhaustports are formed in a portion of the chassis base extending laterallybeyond a lateral edge of the battery. In some embodiments, the exhaustports are directed at a downward angle over a recess formed in theportion of the chassis base extending laterally beyond a lateral edge ofthe battery, thereby preventing obstruction of the exhaust ports if theconcentrator is placed adjacent a flat surface.

In another aspect, an adsorber for a gas concentrator is provided. Theadsorber includes an adsorbent material including adsorbent particlesand a vessel housing the adsorbent material. The vessel includes avessel wall having a non-circular cross section and at least onestiffening support, wherein a combination of a thickness of the vesselwall and a stiffness of the stiffening support is sufficient to limitdeformation of the vessel wall to at least one of less than 0.1 mm andless than 25% of an average diameter of the adsorbent particles under apressure swing of at least 30 psi within the vessel.

In some embodiments, the deformation of the vessel wall is less than0.05 mm under a pressure swing of at least 30 psi within the vessel. Insome embodiments, a cross section of the adsorber is at least 90% filledwith the adsorbent material. In some embodiments, the vessel wall has anoblong cross section. In some embodiments, the at least one stiffeningsupport includes a stiffening rib extending at least one of across aninterior of the vessel and along an interior wall of the vessel. In someembodiments, the at least one stiffening support includes a stiffeningrib positioned on an exterior surface of the vessel. In someembodiments, the adsorber further includes a filter positioned within acavity formed by a protrusion extending from a superior end of thevessel, the protrusion having a cross section different than the crosssection of the vessel wall. In some embodiments, the protrusion iscylindrical. In some embodiments, the protrusion is integrally formedwith the vessel wall.

In another aspect, an adsorber for a gas concentrator is provided. Theadsorber includes an adsorbent material including adsorbent particlesand a vessel housing the adsorbent material. The vessel includes avessel wall having a non-circular cross section and at least onestiffening support, wherein a cross section of the adsorber is at least90% filled with the adsorbent material.

In some embodiments, the vessel wall has an oblong cross section. Insome embodiments, the at least one stiffening support including astiffening rib extending at least one of across an interior of thevessel and along an interior wall of the vessel. In some embodiments,the at least one stiffening support includes a stiffening rib positionedon an exterior surface of the vessel. In some embodiments, the adsorberfurther includes a filter positioned within a cavity formed by aprotrusion extending from a superior end of the vessel, the protrusionhaving a cross section different than the cross section of the vesselwall. In some embodiments, the protrusion is cylindrical. In someembodiments, the protrusion is integrally formed with the vessel wall.

In another aspect, an adsorber system is provided. The adsorber systemincludes a first adsorber including an adsorbent material includingadsorbent particles and a vessel housing the adsorbent material. Thevessel includes a vessel wall having a non-circular cross section and atleast one stiffening support. The adsorber system includes a secondadsorber including an adsorbent material comprising adsorbent particlesand a vessel housing the adsorbent material. The vessel includes avessel wall having a non-circular cross section and at least onestiffening support. The vessel wall of the first adsorber is joined tothe vessel wall of the second adsorber.

In some embodiments, the vessel wall of the first adsorber is integrallyformed with the vessel wall of the second adsorber. In some embodiments,the stiffening support of the first adsorber is aligned with thestiffening support of the second adsorber. In some embodiments, thevessel wall of the first adsorber and the vessel wall of the secondadsorber each comprise an oblong cross section.

In another aspect, a compressor assembly for a portable oxygenconcentrator is provided. The compressor assembly includes a firstcompressor chamber including a first connector, a second compressorchamber including a connector, and a tube including a first endincluding a first connection interface configured to connect to thefirst connector and a second end including a second connection interfaceconfigured to connect to the second connector, wherein the firstconnection interface is shaped to maintain the connection between thefirst connector and the first connection interface in a fixedorientation and the second connection interface is shaped to maintainthe connection between the second connector and the second connectioninterface in a fixed orientation, wherein one or more of the firstconnector, the second connector, and the tube are compliant.

In some embodiments, the first connector has a shape and the firstconnection interface of the tube has a shape that matches the shape ofthe first connector. In some embodiments, the second connector has ashape and the second connection interface has a shape that matches theshape of the second connector. In some embodiments, the shapes of thefirst connection interface, the second connection interface, the firstconnector, and the second connector are square.

In another aspect, a compressor assembly for a portable oxygenconcentrator is provided. The compressor assembly includes a compliantmount including at least one connector. The at least one connectorincludes a compliant member and a pair of protruding tabs extending fromthe compliant member. The compressor assembly further includes acompressor including a first compressor chamber, a second compressorchamber, and at least one pair of slots, the at least one pair of slotsconfigured to receive the pair of protruding tabs of the at least oneconnector.

In some embodiments, the protruding tabs are spaced 180° apart from oneanother around a circumference of the compliant member. In someembodiments, the pair of protruding tabs are formed of a differentmaterial than the compliant member. In some embodiments, the compliantmount is coupled to the compressor by a hollow screw. In someembodiments, intake air is drawn through the hollow screw. In someembodiments, the at least one connector comprises two connectors.

In another aspect, a sensor assembly is provided. The sensor assemblyincludes an oxygen sensor, the oxygen sensor including at least oneemitter including an active surface configured to emit an acousticsignal, at least one receiver including an active surface configured toreceive the acoustic signal, and a body forming a chamber. The bodyincludes a first opening configured to receive the at least one emittersuch that the active surface of the at least one emitter is exposed tothe chamber, a second opening configured to receive the at least onereceiver such that the active surface of the at least one receiver isexposed to the chamber, and at least two reflectors configured toreflect the acoustic signal so as to establish an acoustic path betweenthe active surface of the emitter and the active surface of thereceiver.

In some embodiments, the first opening and the second opening arecoplanar. In some embodiments, the active surface of the emitter and theactive surface of the receiver are coplanar. In some embodiments, theactive surface of the emitter and the active surface of the receiver areoriented to face in parallel directions. In some embodiments, the oxygensensor further includes one or more sealing rings configured to providea seal between the first opening and the emitter and the second openingand the receiver. In some embodiments, the sensor assembly furtherincludes a printed circuit board, wherein the emitter and receiver aremounted to the printed circuit board, and wherein the printed circuitboard is mounted to the body. In some embodiments, the oxygen sensorincludes a temperature sensor configured to measure a temperature ofoxygen gas within the chamber. In some embodiments, the oxygen sensorincludes a temperature sensor configured to measure a temperature of airoutside the chamber. In some embodiments, the oxygen sensor includes apressure sensor configured to measure a pressure of oxygen gas withinthe chamber. In some embodiments, the oxygen sensor includes a pressuresensor configured to measure a pressure of air outside the chamber. Insome embodiments, the sensor assembly further includes a breathdetection sensor.

In another aspect, a method of operating a compressor system isprovided. The method includes determining an efficiency of a compressorconfigured to operate at a plurality of output flow settings. Thecompressor system includes a motor, a power source providing a DC powersource voltage, a voltage controller configured to selectively modifythe power source voltage to provide a plurality of supply voltages, anda pulse width modulation controller configured to selectively applypulse width modulation to the supply voltages at a plurality of pulsewidth modulation duty cycles, thereby providing a plurality of motorcontrol signals. Determining an efficiency of the compressor includesone or more of measuring, calibrating, calculating, or modeling motorefficiency over a range of supply voltage and pulse width modulationduty cycle combinations, each combination comprising a supply voltage ofthe plurality of supply voltages and a pulse width modulation duty cycleof the plurality of pulse width modulation duty cycles. The methodfurther includes selecting a supply voltage of the plurality of supplyvoltages and a pulse width modulation duty cycle of the plurality ofpulse width modulation duty cycles for use at at least one output flowsetting of the plurality of output flow settings based on the determinedefficiency of the compressor, generating the selected supply voltage bymaintaining, reducing, or increasing a nominal supply voltage, andapplying the selected pulse width modulation duty cycle.

In some embodiments, the nominal supply voltage is a desired supplyvoltage for one of the plurality of output flow settings. In someembodiments, the nominal supply voltage is a desired supply voltage fora maximum output flow setting of the plurality of output flow settings.In some embodiments, the power source is one of a battery, a fixed powersource comprising car DC power ports, or an AC to DC power supply. Insome embodiments, the power source is a battery, and the method furtherincludes dynamically monitoring the power source voltage and adjustingone or both of the supply voltage and the pulse width modulation dutycycle to accommodate power source voltage changes to achieve a desiredefficiency of the compressor. In some embodiments. the compressor systemis part of a swing adsorption system and the method further includemonitoring a pressure profile over the course of a pressure swingadsorption cycle, a pressure-vacuum swing adsorption cycle, or a vacuumswing adsorption cycle and dynamically adjusting the supply voltage andpulse width modulation duty cycle to improve efficiency over the courseof the pressure swing adsorption cycle, the pressure-vacuum swingadsorption cycle, or the vacuum swing adsorption cycle. In someembodiments, monitoring the head profile and adjusting the supplyvoltage and pulse width modulation duty cycle are performed during thepressure swing adsorption cycle, the pressure-vacuum swing adsorptioncycle, or the vacuum swing adsorption cycle. In some embodiments,monitoring the head profile includes monitoring one or more of currentmeasurements, power measurements, and pressure measurements through afeed forward process. In some embodiments, the nominal supply voltage isused without pulse width modulation as the motor control signal for ahighest output flow setting of the plurality of outflow settings of thecompressor. In some embodiments, a combination of supply voltageregulation and pulse width modulation are applied to the nominal supplyvoltage to provide motor control signals for one or more output flowsettings lower than the highest output flow setting of the compressor.In some embodiments, the selected supply voltage and the selected pulsewidth modulation duty cycle are selected to optimize efficiency at amost commonly used output flow setting of the plurality of output flowsettings while maintaining the ability to operate at each of theplurality of output flow settings. In some embodiments, the selectedsupply voltage and the selected pulse width modulation duty cycle areselected to reduce switching losses at at least one output flow settingof the plurality of output flow settings. In some embodiments, thevoltage controller is configured to modify the power source voltage toprovide one or more supply voltages higher than the power sourcevoltage.

BRIEF DESCRIPTION OF THE DRAWINGS

Aspects and advantages of the embodiments provided herein are describedwith reference to the following detailed description in conjunction withthe accompanying drawings. Throughout the drawings, reference numbersmay be re-used to indicate correspondence between referenced elements.The drawings are provided to illustrate example embodiments describedherein and are not intended to limit the scope of the disclosure.

FIG. 1A shows a simplified system block diagram of an exemplary portableoxygen concentrator;

FIG. 1B shows an isometric view of internal components of one embodimentof an exemplary portable oxygen concentrator;

FIG. 1C shows a cutaway isometric view of the internal components of oneembodiment of an exemplary portable oxygen concentrator illustratinginternal air flow;

FIG. 1D shows one embodiment of an exemplary portable oxygenconcentrator with a battery;

FIG. 1E shows one embodiment of the portable oxygen concentrator of FIG.1D resting on a side against a flat surface;

FIG. 2 shows an isometric view of one embodiment of an exemplaryportable oxygen concentrator with a removable external housing;

FIGS. 3A and 3B show an illustrative embodiment of an interconnectsystem between the outer housing and the concentrator chassis of oneembodiment of an exemplary portable oxygen concentrator;

FIGS. 4A through 4D, 5A, and 5B show an illustrative embodiment of gasseparation adsorber assembly of an exemplary portable oxygenconcentrator;

FIGS. 6A through 6D show an illustrative embodiment of a batteryretention and alignment assembly of an exemplary portable oxygenconcentrator;

FIGS. 7A through 7K show illustrative embodiments of gas interconnectionelements of an exemplary portable oxygen concentrator;

FIGS. 8A through 8D show various illustrative embodiments of compressormounting elements of an exemplary portable oxygen concentrator;

FIGS. 9A through 9F show various illustrative embodiments of elements ofoxygen and other sensor block arrangements of an exemplary portableoxygen concentrator;

FIGS. 10A through 10F show various illustrative elements of compressormotor control of an exemplary portable oxygen concentrator.

DETAILED DESCRIPTION

Personal use therapeutic oxygen concentrators that convert ambient airinto oxygen enriched gas are increasing in popularity, both in portableand stationary forms. They are generally much smaller in size anddifferent in design as compared to industrial gas concentrators. Anexample portable oxygen concentrator, including its use and operation,is described in co-pending U.S. application Ser. No. 15/427,948,entitled “GAS CONCENTRATOR WITH REMOVABLE CARTRIDGE ADSORBENT BEDS,”which is incorporated herein by reference in its entirety. Anotherexample of such a portable oxygen concentrator is described in U.S.application Ser. No. 15/608,775, entitled “COMPACT PORTABLE OXYGENCONCENTRATOR,” which is incorporated by reference in its entirety.Another example of such a portable oxygen concentrator is described inU.S. application Ser. No. 15/608,788, entitled “GAS CONCENTRATOR WITHREMOVABLE CARTRIDGE ADSORBENT BEDS,” which is incorporated herein byreference in its entirety. Such oxygen concentrators, because of theirsmall size and intended personal use, have differing designconsiderations from large industrial concentrators intended to producelarge quantities of concentrated gas. For example, in an illustrativeembodiment, the portable concentrator according to the presentdisclosure may be between 25 and 200 cubic inches in size, between 2 and7 pounds in weight, and may produce between 300 and 3000 ml/min ofconcentrated oxygen.

FIG. 1A is a schematic illustration of an exemplary oxygen concentratorsystem 100 in accordance with an embodiment of the present disclosure.As shown in FIG. 1A, the system 100 generally includes an air inlet 1through which ambient air is drawn into the system, a compressorassembly 2 for pressurizing the ambient air to provide a feed gas, a gasseparation unit or system 3 which receives and processes the feed gas toproduce a product gas having a higher oxygen content than the ambientair, a gas delivery system 7, such as a conserver, for delivering theoxygen-rich product gas to a patient, and an exhaust outlet or port 6for releasing nitrogen-rich waste gas and spent cooling airflow gas. Asused herein, spent cooling airflow gas can refer to airflow gas that hasbeen used to cool portions of the concentrator system 100. The system100 further includes a feed/waste manifold 9, a product valve manifold10, a product gas storage 4, a user/data interface 8, and a programmablecontroller 5 for controlling the operation of the system.

In some embodiments, ambient air drawn into the system through air inlet1 can be used to supply the gas separation system 3 with pressurized gasto flush out nitrogen-rich waste gas. Ambient air drawn into the systemthrough the air inlet 1 can also be used to cool the internal componentsof the system. This air movement may be provided by an airflowgenerator, such as a fan or blower, located at the air inlet 1, at theexhaust outlet 6, or along an air flow path between the air inlet 1 andthe exhaust outlet 6. To achieve proper air flow, an airflow generatormay be employed in some embodiments. In some embodiments, airflow may begenerated, for example, by a cooling fan or blower. In some embodiments,the cooling fan or blower can have dimensions in the range of 40 mm×40mm to 100 mm×100 mm in diameter and 20 mm to 60 mm in depth. One or morefans in varying sizes and locations may also be employed in someembodiments to optimize air flow and minimize noise. As indicatedschematically in FIG. 1A, the air flow may be directed to pass over theinternal components of the oxygen concentrator system 100. In someembodiments, the waste gas from the gas separation system 3 and thespent cooling gas both exit the system 100 via the exhaust outlet 6. Insome embodiments, the exhaust outlet 6 is positioned adjacent orimmediately adjacent the compressor assembly 2. In some embodiments, theair flow path directs cool air to pass over the other components of thesystem before reaching the compressor assembly 2. The compressorassembly 2 can generate significant heat during operation. In someembodiments, the compressor assembly 2 is placed adjacent to the exhaustoutlet 6 to achieve improved cooling effectiveness. In some embodiments,an airflow generator, such as a fan, blower, or other means, may bepositioned along the air flow path to push and/or pull air through thesystem 100 interior from the air inlet 1 to the exhaust outlet 6 orbetween the air inlet 1 and the exhaust outlet 6. In some embodiments, aplurality of air inlets and/or a plurality of exhaust outlets may beemployed to achieve appropriate cooling. In some embodiments, theconcentrator 100 can include a plurality of airflow generators toachieve appropriate cooling.

In some embodiments, the gas separation system 3 is a pressure swingadsorption (PSA) gas separation system. In some embodiments, the gasseparation system 3 is a vacuum swing adsorption (VSA) system. In someembodiments, the gas separation system 3 is a vacuum pressure swingadsorption (VPSA) system. The gas separation system 3 may include one ormore adsorbers. The adsorbers can employ pressure, vacuum, or acombination thereof to separate the components of ambient air to producean oxygen-rich product gas. Ambient air is drawn in by the compressorassembly 2 through a filter and through an elongated and/or tortuous airpath designed to minimize the escape of noise caused by the compressorassembly 2. In some embodiments, the compressor assembly 2 may include asingle cylinder or multi-cylinder reciprocating piston compressoremploying pressure or a combination of pressure and vacuum cylinders. Insome embodiments, the compressor assembly 2 may alternatively oradditionally include other compressors types such as scroll, linear freepiston, rotary vane, rotary screw, conical screw, or diaphragm typecompressors.

Pressurized air may be discharged from the compressor assembly 2 at arate of 5 SLPM to 15 SLPM per LPM or approximately 5 SLPM to 15 SLPM perLPM of oxygen-rich gas produced at a pressure up to 3 bar. Thepressurized air is directed to one of two or more adsorbers of the gasseparation system 3 by one or more feed/waste valves that may be housedin a feed/waste manifold 9. The feed/waste valve configuration in thefeed/waste manifold 9 can vary by embodiment and may include one or moresolenoid valves, piezoelectric valves, air piloted valves, rotaryvalves, cam actuated valves, and/or diaphragm valves. In someembodiments, the feed/waste valves may be decoupled from the compressorassembly 2, adsorbers of the gas separation system 3, and otherstructural components to reduce transmission of noise from the valves toother system components or the exterior of the oxygen concentratorsystem 100. A valve fluid path may be connected with compliant membersto achieve an appropriate level of mechanical isolation, and thefeed/waste manifold 9 or valve mounting can be additionally isolatedfrom other components. Alternatively, in some embodiments, the valvesmay be directly mounted to relatively high-mass, high densitycomponents, such as a compressor head of the compressor assembly 2 orthe adsorbers of the gas separation system 3 to reduce noisetransmission. These components may also then be isolated from othercomponents in the system, particularly large plastic bodies such ashousings or chassis components. The feed/waste valves contained infeed/waste manifold 9 can additionally direct exhaust nitrogen-rich gasfrom the adsorbers of the gas separation unit 3 to a muffler in apressure swing adsorption (PSA) system or to a vacuum pump in a vacuumswing adsorption (VSA) or vacuum pressure swing adsorption (VPSA)system.

In some embodiments, the adsorbers of the gas separation system 3 aredesigned to be removable and replaceable as described in the aboveincorporated references. Each adsorber can include an adsorbent materialand a vessel housing the adsorbent material. The adsorbent material canbe in the form of an adsorbent bed. The adsorbent bed may contain atleast one pretreatment adsorbent layer that is directed to water andcarbon dioxide removal to prevent contamination of a main layeradsorbent. In some embodiments, this material may be a desiccant such asactivated alumina or silica gel. In alternate embodiments, thepretreatment layer may contain a sodium or lithium exchanged zeolite.The adsorbent bed can also include a main layer adsorbent that isdirected to separate oxygen from nitrogen in ambient air. The main layeradsorbent may be a lithium exchanged zeolite material. Nitrogen isretained in the adsorber, while oxygen-rich gas is allowed to passthrough the adsorber into the product valves or product valve manifold10.

The product valve manifold 10 may include one or more of solenoidvalves, piezoelectric valves, air piloted valves, rotary valves, camactuated valves, or diaphragm valves, check valves, and orifices tocontrol gas flow. The product valve manifold 10 connects to theadsorbers of the PSA gas separation system 3 and may be decoupled fromthe adsorbers and other structural components to reduce noisetransmission and vibration between valves and other components in thesystem. The product valve manifold 10 may also be part of a commonassembly with the feed/waste valve manifold 9 with appropriate portionsof the valve directing gas into and out of the adsorbers.

In some embodiments, oxygen-rich gas flows from the product valvemanifold 10 to an integrated assembly that is directed to product gasstorage 4, oxygen gas concentration measurement, oxygen gas pressure andtemperature sensing, as well oxygen gas filtration, and oxygen gasdelivery, e.g. a gas delivery system 7. In some embodiments, the gasdelivery system 7 can be a conserver. In some embodiments, theintegrated assembly contains multiple sensors 11 for various functionsincluding ambient pressure sensing, oxygen gas pressure measurement,breath pressure or cannula pressure measurement, and temperaturemeasurement.

The control of the oxygen concentrator system 100 can be achieved by aprogrammable controller 5. The oxygen concentrator system 100 also maycontain a user/data interface 8. The user/data interface 8 can includeone or more buttons or other inputs to control various features orfunctions of the concentrator system 100 such as, for example, powerstate, oxygen flow rate, and or any other concentrator system function.Other embodiments additionally contain an LCD display, at least oneremovable and rechargeable battery, and an integrated oxygen conservingdevice to deliver oxygen gas synchronously with a patient's onset ofinhalation to maintain clinical efficacy while reducing the amount ofoxygen-rich gas delivered to the patient by a factor of about 2:1 to9:1.

FIGS. 1B-1E and FIG. 2 illustrate an embodiment of the oxygenconcentrator system disclosed herein in the form of a portable oxygenconcentrator 100 a. The concentrator system 100 a can include any of thesame or similar features and functions as the concentrator system 100.FIGS. 1B and 1C are interior isometric views taken from two opposingsides of the oxygen concentrator 100 a. As shown in FIG. 1B, theportable oxygen concentrator 100 a includes a dual function chassis base111. The chassis base 111 can serve as a support for the internalcomponents of the oxygen concentrator 100 a. The chassis base 111 canalso serve as a mount for a power source, such as a battery.

As shown in FIGS. 1B and 1C, the portable oxygen concentrator 100 afurther includes one or more adsorbers 140 positioned on one end of thechassis base 111, a compressor assembly 190, and a shell structure 195.In some embodiments, the adsorbers 140 are non-cylindrical adsorbers.The vessels forming the adsorbers 140 can be generally non-cylindricalin shape.

As shown in FIG. 1C, the oxygen concentrator 100 a includes an outerhousing 115 coupled to the chassis base 111 so as to define an internalvolume enclosing elements of the concentrator system 100 a, such as theadsorbers 140, an airflow generator 165, the compressor assembly 190,and the shell structure 195. In some embodiments, the shell structure195 can include one or more insulating panels 195 a-c disposed about thecompressor assembly 190. In some embodiments, the shell structure 195can surround the compressor assembly 190. In some embodiments, the shellstructure 195 is configured to separate the cooling airflow in theoxygen concentrator system 100 a from the higher temperature, spentairflow adjacent the compressor assembly 190 that is ready to beexpelled from one or more exhaust outlets or ports 161. In someembodiments, the shell structure 195 forms at least a portion of anenclosure or at least partially sealed chamber around the compressorassembly 190. In some embodiments, insulating panels 195 a-c can bedisposed adjacent the compressor assembly 190, for example, in an angledarrangement, which together with the other components surrounding thecompressor assembly 190 (e.g., printed circuit board) form an enclosureor at least partially sealed chamber that impedes or prevents heattransfer from the higher temperature, spent airflow to the coolingairflow. In some embodiments, a printed circuit board, such as printedcircuit board 150 as shown in FIG. 2, can form at least a portion of anenclosure or at least partially sealed chamber around the compressorassembly 190. In some embodiments, an interior surface of the housing115 can form at least a portion of an enclosure or at least partiallysealed chamber around the compressor assembly. In some embodiments, theshell structure 195 can separate the compressor assembly 190 from one ormore other elements positioned within the internal volume defined by thehousing 115, such as the adsorbers 140.

The portable oxygen concentrator 100 a further includes one or morepneumatics modules, sensor modules, and display modules. As shown inFIGS. 1B-C, in some embodiments, the one or more pneumatics modules,sensor modules, and display modules can be formed as a combined upperpneumatics, sensor, and display module 145 that can be detachablyremoved as a unit. In some embodiments, the shell structure 195 canseparate the compressor assembly 190 from one or more pneumaticsmodules, one or more sensor modules, one or more electronic modules, orother elements of the concentrator system.

The oxygen concentrator 100 a further includes one or more userinterface controls 175, a control electronics printed circuit board(PCB) (not shown), one or more electrical connectors 120 adapted to matewith connectors coupled to the housing 115, and a printed circuit board(PCB) 170. The printed circuit board 170 can be a user interfacedisplay/sensor PCB or sensor block PCB, or include both. The printedcircuit board (PCB) 170 can include various control sensors such asoxygen purity, pressure, and temperature sensors. In some embodiments,the printed circuit board 170 can include or be coupled to a userinterface display 171. In some embodiments, the upper pneumatics,sensor, and display module 145 includes an interface manifold 147 thatcan be removably attached to an end of the adsorbers 140 and the productmanifold. In some embodiments, the control sensors can be electricallyconnected to the interface. In some embodiments, the shell structure 195in combination with the PCB 150 and a top portion of the housing 115 canenclose the compressor assembly 190 in a chamber or “hot box” in whichhot air is retained, for example, by creating an enclosure or at leastpartially sealed chamber around the compressor assembly 190. Thischamber or hot box can separate airflow from an airflow generator, suchas a fan or blower, into hotter air adjacent the compressor and coolerair outside the hot box.

FIG. 1C shows an implementation of the cool to hotter airflow control asdescribed above. In this airflow implementation, an airflow generator165 is mounted directly over the compressor assembly 190. The airflowgenerator 165 can be a blower or fan. The outer housing 115 can includeone or more air inlets 160 a-b. The air inlets 160 a-b can be recessedwithin the outer housing 115 or extend along a curved or angled surfaceof the outer housing 115. In some embodiments, the air inlet 160 a andthe air inlet 160 b can be positioned on different faces or surfaces ofthe outer housing 115. In some embodiments the air inlet 160 a and theair inlet 160 b can be positioned on opposite surfaces of the outerhousing 115. Air can be drawn in from two sides of the oxygenconcentrator 100 a through the air inlets 160 a and 160 b disposed onopposing sides of the oxygen concentrator 100 a. In alternativeembodiments, the air inlet 160 a and the air inlet 160 b can bepositioned on the same face or surface of the outer housing 115. In someembodiments, internal components can be positioned such that cooleroutside air flows over most of the internal components before beingdirected to the vicinity of the compressor assembly 190.

The airflow generator 165 is configured to direct airflow along anairflow path between the one or more air inlets 160 a-b and one or moreexhaust outlets or ports 161. In some embodiments, one or more exhaustports 161 can be positioned within the chassis base 111. In someembodiments, the chassis base 111 can include exhaust ports 161 onopposite side surfaces of the chassis base 111. Both exhaust gas fromthe PSA gas separation unit and the fully downstream spent cooling gasare exhausted through exhaust ports 161 on each side of chassis base111. In alternative embodiments, the exhaust ports 161 can be positionedon the same side of the chassis base 111. In some embodiments, highertemperature, spent cooling airflow is confined to the area surroundingthe compressor assembly 190 and exhausted immediately adjacent thebottom of the compressor assembly 190. This is an example of a push/pullairflow in which the compressor assembly 190 is positioned at adownstream end of the airflow path immediately before the exhaust ports161. Such an arrangement can accomplish the delivery of cool air to manyof or most of the internal components before exhausting hot air from thehigher temperature components in the vicinity of the compressor assembly190. In some embodiments, it is desirable to exhaust hot air in thevicinity of the compressor assembly as soon as possible, for example, toreduce backflow of the higher temperature air from the vicinity of thecompressor assembly 190 to other internal regions of the concentrator100 a. The positioning of the exhaust ports 161 adjacent to thecompressor assembly 190 can reduce such a backflow. Advantageously, thecooling air flow path of the oxygen concentrator system 100 a ends at anarea adjacent the component that generates the most heat, for example,the compressor assembly 190, so that the spent cooling air can beexpelled before affecting other components.

The oxygen concentrator 100 a is configured to minimize the likelihoodof impeding the airflow through the device in as many use situations aspossible such as, for example, placing the oxygen concentrator 100 aagainst a flat vertical surface or laying the concentrator 100 a on itsside (other than the intended bottom side). The air inlets 160 a and 160b are designed and arranged to substantially reduce the risk of inletvent obstruction. The exhaust ports 161 are contoured such that theycannot be blocked by any single plane. In one embodiment, the exhaustports 161 are disposed on only one side of the chassis base 111 suchthat the ports 161 directs hot exhaust gas away from the patient's bodywhen the oxygen concentrator 100 a is being carried adjacent to thepatient body such as in a shoulder bag or hip bag. In some embodiments,the design of the air inlets 160 a-b and/or exhaust ports 161 caninclude additional geometrical details such as curvature of a face ofthe air inlets 160 a-b and/or exhaust ports 161, recessing of the airinlets 160 a-b and/or exhaust ports 161 below the surface of theconcentrator housing 115, and/or angling of the exhaust ports 161 todirect both air flow and noise in a desirable direction as it exits theconcentrator system 100 a. In some embodiments, the exhaust ports 161are angled away from a removable battery 110 coupled to the chassis base111 to prevent heating of the battery 110. In some embodiments, theexhaust ports 161 can be formed in a portion of the chassis base 111extending laterally beyond a lateral edge of the battery 110. In someembodiments, the exhaust ports 161 are directed at a downward angle overa recess formed in the portion of the chassis base 111 extendinglaterally beyond a lateral edge of the battery 110. The angling andpositioning of the exhaust ports 161 can prevent obstruction of theexhausts ports 161 if the concentrator is placed against or adjacent aflat surface.

In one embodiment, each air inlet 160 a-b includes an opening defined byan exterior border 162 a-b that is recessed from a portion of theexterior surface of the housing 115, which may have a planar or convexcontour. In some embodiments, the recessed exterior borders 162 a-b ofthe air inlets 160 a-b in combination with the convex contour of theexterior surface of the housing 115 form an air gap that permits atleast some air to flow through even when the exterior surface of thehousing is resting against a planar surface such as a table top. In someembodiments, a middle section of each exterior border 162 a-b is notcoplanar with the opposing end sections such that the middle sectionslightly protrudes from the opposing end sections. In some embodiments,the air inlets 160 a-b comprise louvers having a curved configurationadapted to increase intake of airflow from multiple directions.

FIG. 1D shows the oxygen concentrator 100 a having the battery 110slidably mounted to a lower surface 166 of the chassis base 111. As alsoshown in FIG. 1D, a plurality of the exhaust ports 161 are disposedhorizontally along a lower edge 164 of the chassis base 111. Eachexhaust port 161 comprises a recessed opening 163 defined by an exteriorborder that is disposed on the sidewall 168 and lower surface 166 of thechassis base 111. The recessed opening 163 extends into the sidewall 168and partially into the lower surface of the chassis base 111 so as toform an opening that allows for at least two airflow paths 169 a-b fromthe oxygen concentrator. In some embodiments, the airflow paths 169 aand 169 b can be offset. In some embodiments, the airflow paths 169 aand 169 b can be perpendicular or generally perpendicular. As FIG. 1Dfurther shows, at least a portion of a lateral side 112 of the battery110 is recessed such that when the battery 110 is mounted to the chassisbase 111, the sidewall 168 of the chassis base 111 protrudes outwardlyfrom the recessed portion of the lateral side 112 of the battery 110thereby exposing the recessed opening 163 of each exhaust port 161.Additionally, the battery recess near the exhaust ports 161 providesadditional space for the exhaust gas heat to dissipate with minimalcontact to the battery housing, which minimizes the amount of exhaustgas heat which may be transferred to the battery 110. Minimizing batteryheating is advantageous to battery performance and life, particularly ifthe heat is specific to a portion of the battery such as the smallregion surrounding the exhaust outlets. FIG. 1E shows the oxygenconcentrator 100 a resting against a flat surface 200 on the side wherethe exhaust ports 161 are located. As shown in FIG. 1E, the recessedopenings 163 of the exhaust ports 161 are not obstructed even though theside with the exhaust ports 161 is resting against a planar surface. Theconfiguration of the exhaust ports 161 in combination with the batterydesign enable air 169 b to still flow out of the exhaust ports 161. Inone embodiment, the exhaust ports 161 comprise louvers having aconfiguration adapted to direct air to flow in an angled direction.Combined, these features increase the likelihood of full or partial airflow helping to prevent overheating even if the oxygen concentrator 100a is improperly positioned during use.

As described in co-pending application Ser. No. 15/608,775, one way toimplement a portable oxygen concentrator package is to mount theinternal workings, e.g., the adsorbers, valves, compressor andcontroller elements to a chassis and cover the chassis and internalelements with a removable outer housing. Such an arrangement is shown inFIG. 2. The outer housing 115 is configured to removably couple to thechassis base 111. As shown in FIG. 2, the outer housing 115 containsuser interface elements including one or more user interface controls175. The user interface controls 175 can be electrically connected tothe PCB 170. The PCB 170 can be mounted to a superior end of the chassisbase 111. In addition, as shown in FIG. 2, the interior components ofthe oxygen concentrator 100 a are designed and arranged in a manner suchthat the overall exterior contour created by the interior componentssubstantially conforms to the rectangular shaped outer housing 115 so asto reduce waste of space inside the housing 115. For example, the twoadsorbers 140 positioned on one end of the chassis form an exteriorcontour containing somewhat flattened sides with rounded corners tomirror the configuration of the outer housing 115. The PCB 150 ispositioned in a vertical orientation along a lateral side of the chassisto mirror the flat lateral side of the outer housing 115.

FIGS. 3A and 3B show an improved design for making the electricalconnection between the outer housing 115 and the interior components ofthe oxygen concentrator 100 a. As shown in FIG. 3A, the outer housing115 can include one or more electrical connectors 125 in electricalcommunication with the electrical components of the outer housing 115,such as the user interface controls 175. The electrical connectors 120can reside on the PCB 170. The electrical connectors 125 can bepositioned to align with and mate with the electoral connectors 120 whenthe outer housing 115 is coupled to the chassis base 111.

The outer housing 115 can be configured to define an enclosed volumearound the printed circuit board 170 when coupled to the chassis base111. The outer housing 115 can be configured to seal the printed circuitboard from external moisture when coupled to the chassis base 111.

The connectors 120 can be oriented on the PCB 170 so as to face in agenerally superior direction. The connectors 125 can be positioned on aninterior surface of a top wall of the housing 115, and may be orientedto face in a generally inferior direction. During assembly of the oxygenconcentrator 100, the outer housing 115 can be traversed generallyinferiorly over the internal components of the oxygen concentrator 100and mated with the chassis 111. These connectors are disposed such thatwhen the outer housing 115 is mated to chassis 111, connectors 120 and125 mate. This arrangement can facilitate ease of manufacture andimproved sealing of the housing 115 and chassis 111. This arrangementallows for establishment of an electrical connection and a mechanicalconnection without requiring additional external openings in the outerhousing that could provide access to moisture.

One of the drivers in making a portable oxygen concentrator as small andlight as possible is to optimize the operation of the adsorbers 140 ofthe PSA gas separation unit 3. In general, each adsorber 140 contains anadsorbent material 141 that filters at a molecular level. In someembodiments, the adsorbent material 141 is in the form of an adsorbentbed. In some embodiments, the adsorbent material 141 can filter betweennitrogen and oxygen molecules in a manner described above and otherwiseemployed in gas separation devices including portable oxygenconcentrators. In some embodiments, the adsorbent material 141 caninclude adsorbent particles. Many conventional portable oxygenconcentrators utilize zeolite beads for this molecular filter material.These adsorbent particles are densely packed into an adsorbent bedvessel or pressure vessel 144. The vessel 144 and the adsorbent material141, possibly in combination with other components, can form theadsorber 140. To work effectively and achieve reasonable operationallifetimes, it is important that the adsorbent particles are packedclosely and are constrained from movement during PSA cycles when theadsorbers 140 may be subject to zero to 10's of PSI over the course of afew seconds. Portable oxygen concentrators typically utilize adsorbers140 having vessels 144 with circular cross-sections, such as those shownin FIG. 4A, for example, because a circular cross section allows forthin vessel walls 148 with no or little deformation, keeping theadsorber designs light while ensuring rigidity. However, many oxygenconcentrator housing 115 shapes are rectangular solids, typically withsome curvature. As shown in FIGS. 4A, 4B, and 4C, a circular crosssection vessel 144 is not an efficient way to maximize capacity if thecircular columns have to fit into a more or less rectangular shape.

In some embodiments, vessels 144 having non-circular cross sections areused. However, once a vessel 144 design deviates from a circularcross-section, the surfaces, particularly any resulting flat surfacesare more prone to deformation under pressure. One way to counteractpotential deformation is to utilize thicker vessel walls 148 as shown inFIG. 4B. However, thicker vessel walls 148 may diminish the advantage inspace gained by using the non-circular cross-section shape and addweight rather than performance to the oxygen generating system.

FIG. 4D shows a vessel shape tailored to utilize most of the space atone end of the outer housing 115 in the oxygen concentrator 100 a shownabove. The shape of the vessel 144 shown in FIG. 4D is non-circular incross section. In some embodiments, such a shape can include flatdeformation prone surface areas.

As shown in FIG. 5A, in some embodiments, the adsorbers 140 can includestiffening supports 146 to stiffen the vessel 144 in a direction oflikely deformation. In some embodiments, the stiffing supports 146 canbe stiffening ribs. In some embodiments, the stiffening supports 146 canextend across an interior of the vessel 144. In some embodiments, thestiffening supports 146 can extend along an interior wall of the vessel144. In some embodiments, each adsorber 140 can include a singlestiffening support 146. In some embodiments, each adsorber 140 caninclude a plurality of stiffening supports 146. In some embodiments,each adsorber 140 can include one or more stiffening supports 146extending across an interior of the vessel 144 and/or one or morestiffening supports 146 extending along an interior wall of the vessel144.

In some embodiments, one or more stiffening supports 146 mayalternatively or additionally be added on an exterior portion of thevessel 144. In some embodiments, one or more stiffening supports 146 canbe positioned on an exterior surface of the vessel 144.

Adding features to stiffen the structure at the point of deflection cansubstantially mitigate the deformation with minimum added weightrelative to changing the overall wall thickness. In one embodiment, theadsorber system comprises two adsorbers 140 having vessels 144 withoblong, obround, semicircular, or generally semicircular cross-sectionsjoined together. In addition, the non-circular vessels 144 allow moreadsorbent material to be placed in the same internal concentratorvolume, which in turn increases the oxygen delivery capacity of theoxygen concentrator without increasing the size. In some embodiments, across-section of the adsorber 140 can be at least 90% filled withadsorbent material 141. In some embodiments, a cross-section of aportion of the adsorber 140 housing adsorbent material 141 can be atleast 90% filled with adsorbent material 141. In some embodiments, theportion of the adsorber 140 filled with adsorbent material 141 can befilled such that at any cross-section of the portion the adsorber 140 isat least 90% filled with adsorbent material 141.

In some embodiments, a combination of a thickness of the vessel wall 148and a stiffness of the stiffening support 146 is sufficient to limitdeformation of the vessel wall 148 to at least one of less than 0.1 mmand less than 25% of an average diameter of the adsorbent particlesunder a pressure swing of at least 30 psi within the vessel 144. In someembodiments, a combination of a thickness of the vessel wall 148 and astiffness of the stiffening support 146 is sufficient to limitdeformation of the vessel wall 148 to less than 0.05 mm under a pressureswing of at least 30 psi within the vessel 144.

For suitable vessel materials, e.g. materials with suitablestiffness/weight, such as aluminum, magnesium, or plastics materials, ithas been found that a combination of wall thickness/support ribstiffness equivalent to achieving maximum deformation of 25% of theadsorbent material particle size under a pressure swing of 30 psi makespossible a shape such as shown in FIG. 4D, an optimized non-circularcross section for a particular shaped volume, with a wall thickness assmall as 0.030 inches in a cast magnesium or aluminum material alongwith strengthening ribs. Other materials and volume shapes may beaddressed using similar constraints.

As shown in FIG. 4D-5B, in some embodiments, an adsorber system caninclude a plurality of adsorbers 140. In some embodiments, the adsorbersystem can include a first adsorber 140 and a second adsorber 140. Insome embodiments, the vessel wall 148 of the first adsorber 140 isjoined to the vessel wall 148 of the second adsorber 140. In someembodiments, the vessel wall 148 of the first adsorber 140 is integrallyformed with the vessel wall 148 of the second adsorber 140. In someembodiments, the stiffening support 146 of the first adsorber 140 isintegrally formed with the stiffening support 146 of the second adsorber140. As shown in FIG. 5B, in certain embodiments, filters 147 can berecessed within cavities 152 at a superior end of the adsorber 140. Insome embodiments, the cavities are defined by the wall 148. In someembodiments, the cavities 152 have a cross-section with a different sizeand/or shape relative to the inferior portions of the adsorber 140. Forexample, the cavities can be formed by generally disc-shaped protrusions153. In some embodiments, the cavities 152 can be formed withinprotrusions 153 extending from a superior end of the vessel 144. Theprotrusions 153 can have a cross section different than a cross sectionof the vessel wall 148. In some embodiments, the protrusion 153 iscylindrical. In some embodiments, the protrusions 153 are integrallyformed with the vessel walls 148.

Recession of the filters 147 within the cavities can allow for use offilters or flites having a different shape and/or size relative to thevessel wall 148 of the adsorber 140. For example, recessing the filters147 within the cavities can allow for use of a round filter or frit witha vessel 144 having a non-circular cross-section.

As shown in FIG. 5B, the adsorber 140 can be sealed at its bottom endvia a plate 149 having O-rings 151.

In some embodiments, the walls 148 may have a uniform or variable wallthickness.

As shown in FIG. 2, and shown in co-pending U.S. application Ser. No.15/608,775, in some embodiments, the battery 110 may act as a suitablebase for the portable oxygen concentrator 100 due to its ability tocreate a low center of gravity for the oxygen concentrator itself.

In previous oxygen concentrator designs produced by the Applicant, abattery has two raised slides in the form of shaped bars extending alongpart of the length of each side of the battery. The slides can fit intorails on a concentrator chassis base. The slides are placed in therails, and the battery is slid onto the chassis until electricalconnectors from the battery and chassis base are mated and a retainermating piece contacts a hand actuated retainer. The combination of themated electrical connector, the relatively long slide/rail connection,and the retainer serves to hold the battery in place within the chassisbase. Removal consists of releasing the retainer and sliding the batteryout.

FIGS. 6A-D show an embodiment of an arrangement for securing a battery110 to a chassis base 111. FIG. 6A shows the battery 110 separated fromthe chassis base 111. FIG. 6C shows the battery 110 coupled to thechassis base 111.

As shown in FIGS. 6A-D, the oxygen concentrator 100 includes rails 113a-b. The first rail 113 a is configured to receive a first slide 114 aof a battery 110. The second rail 113 b is configured to receive asecond slide 114 b of the battery 110. The second rail 113 b can bespaced apart from the first rail 113 a so as to form a channel 116 forreceiving the battery 110. The channel 116 can include an open proximalend 117 a and a closed distal end 117 b.

As shown in FIG. 6A, the rails 113 a-b include a flexible stiffeningmechanism 129. The flexible stiffening mechanism 129 is configured toimpart a biasing force on a surface 127 of the battery 110 when thebattery 110 is received in the channel 116.

In certain embodiments, the flexible stiffening mechanism 129 includes abump or protrusion 133 a. The protrusion 133 a projects from the firstrail 113 a towards the second rail 113 b. The flexible stiffeningmechanism also includes a slit 130 positioned behind the protrusion. Theslit 130 can be configured to facilitate or allow for travel of theprotrusion 133 a fore and aft (i.e., towards the second rail 113 b oraway from the second rail 113 b). In some embodiments, the slit 130 canfacilitate or allow for flexion of the section of the rail from whichthe protrusion 133 a projections. For example, in some embodiments, theslit 130 can be positioned, shaped, dimensioned, or otherwise configuredto allow for movement of the section of the rail from which theprotrusion 133 a projects. In certain embodiments, the protrusion 133 amay alternatively or additionally be deformable so as to facilitateflexion of the protrusion 133 a. In certain embodiments, the stiffeningmechanism 129 can maintain contact between the first rail 113 a and thebattery 110 to stabilize the battery 110 within the channel 116, forexample, while the battery 110 is inserted into the channel 116 andwhile the battery 110 is fully seated within the channel 116. FIGS. 6Band 6D depict the flexible stiffening mechanism before and after,respectively, a portion of the battery 110 contacts the flexiblestiffening mechanism 129, for example, during an insertion of thebattery 110 into the channel 116.

In certain embodiments, the biasing force 110 of the flexible stiffeningmechanism 129 is sufficiently flexible to permit translation of thebattery 110 within the channel 116 past the protrusion 133 a.

Incorporating a flexible stiffening mechanism 129 to the batteryattachment of a portable oxygen concentrator 100 can facilitatealignments of smaller and more tightly spaced electrical connections,such as an electrical connector 126 of the battery 110 and an electricalconnector 128 of the concentrator 100. In the absence of a flexiblestiffening mechanism, at one end of manufacturing tolerances of abattery and a concentrator, some combinations may bind or be difficultfor the customer to install. Conversely, at the other end of themanufacturing tolerances, the battery may rattle or cause intermittentor undependable electrical connections between the battery and theconcentrator. Use of the flexible stiffening mechanism 129 canfacilitate increased stability when using a battery 110 that has a sizesmaller than an upper tolerance level to reduce installation difficulty.In some embodiments, the flexibility of the stiffening mechanism 129 canfacilitate contact between a batteries 110 having different sizes. Forexample, in some embodiments, the stiffening mechanism 129 canfacilitate contact between the first rail 113 a and a battery 110 havinga size that is smaller than an upper tolerance level of battery sizescapable of being received within the channel 116. As described herein,the increased stability can reduce rattle of the battery 110, forexample lateral movement of the battery orthogonal to an axis alongwhich the battery 110 is inserted, and loss of the electricalconnections between the battery and concentrator.

In some embodiments, the flexible stiffening mechanism 129 is configuredto impart the biasing force on the surface 127 of the battery 110 so asto align the electrical connector 126 of the battery 110 with theelectrical connector 128 of the concentrator 100 a. By improvingalignment of the electrical connections, wear and tear resulting frombattery attachment can be reduced.

In some embodiments, one or more protrusions can project from the secondrail 113 b at least partially towards the first rail 113 a. The one ormore protrusions projecting from the second rail 113 b can be configuredto contact the battery 110 when the battery 110 is positioned within thechannel 116. In some embodiments, at least one protrusion 133 bprojection from the second rail 113 b is positioned proximally relativeto the protrusion 133 a. In at least some embodiments, at least oneprotrusion 133 c projecting from the second rail 113 b is positioneddistally relative to the protrusion 133 a. In certain embodiments, theflexible stiffening mechanism 129 is configured to impart the biasingforce on the surface 127 of the battery 110 to impart stability to theinstallation of the battery 110.

In some embodiments, the protrusions 133 a-c can form a three pointstiffening hold. The protrusions 133 a-c can be positioned on the rails113 a-b so that they lightly contact the battery 110 structure when thebattery 110 is received within the channel 116. The protrusions 133 a-ccan be sized to contact the battery 110 when inserted into the channel116, but also allow the battery 110 to be slid along the rails 113 a-bfrom the open proximal end to the closed distal end, e.g., by providingone or more forces, such as the biasing force of the flexible stiffeningmechanism and/or one or more frictional forces, upon the battery 110 ofa sufficient magnitude to allow movement of the battery when an externalforce above a threshold magnitude is applied thereto, but restrictmovement of the battery 110 when an external force below a thresholdmagnitude is applied thereto.

The flexible stiffening mechanism 129 and the protrusions 133 b-c canprovide an improved coupling of the battery 110 onto the rails 113 a-b.This flexion of the stiffening mechanism 129 can achieve better batteryengagement and alignment than previous designs without adding space,weight, or cost.

While a single flexible stiffening member 129 on a first rail 113 a isdescribed, it is contemplated that a plurality of flexible stiffeningmembers 129 can be employed on one or both of the rails 113 a-b. Whilethe flexible stiffening mechanism is described as having a protrusion133 a and a slit 130, other suitable flexible stiffening mechanisms orspring mechanisms may be employed. While two protrusions, protrusions133 b and 133 c, on the second rail 113 b are described, it iscontemplated that one protrusion or more than two protrusion 133 b-c canbe employed on one or both of the rails 113 a-b.

As described herein, portable oxygen concentrators can benefit fromdesigns that are compact in size and internally simple. Due to the flowof gas through a portable oxygen concentration, multiple gas tightinterconnections can be required within the interior of the portableoxygen concentrators. Barbed connections are commonly used in portableoxygen concentrators, in which a compliant tube is stretched over a barbon the end of a mating piece. Barbed connections can be limited to smallnumbers of in line connections both in terms of manufacturability of atwo-dimensional arrangement of barbed fittings and in difficulty ofinstallation and removal of tubes from such a two-dimensionalarrangement.

An improved approach to multiple gas connections in one-piece parts isshown in FIGS. 7A-C. A multi-port interconnection 181 is shown inseveral views with tubes 180 mated thereto. In some embodiments, theinterconnection 181 can be compliant or elastomeric. In someembodiments, the interconnection 181 can be formed of a single piece.The interconnection 181 can include a plurality of ports 184, each portconfigured to receive a tube 180. Each port can include one or moresealing rings 182. In some embodiments, each sealing ring 182 can be inthe form of a raised bump on the inside wall of one of the ports 184 ofthe multi-port connector 181, is employed. Tubes 180 are pressed intothe ports 184 of the interconnect 181 until they pass the sealing ring182. The compression of both the compliant interconnect piece 181 aswell as the tubes 180 around the sealing ring 182 provides sealingand/or positioning functions. The raised bump can be circular in someembodiments, but may be any other suitable shape, such as rectangular ortriangular. Such an arrangement lends itself to manufacturability andusability for multiple two-dimensional port arrangements such as shownin FIG. 7C.

In some embodiments, compression around the sealing ring 182 of one port184 can extend into adjacent ports 184 if not addressed. To reduce thespacing required between the ports 184 to achieve a higher densitymulti-port interconnect 181, in some embodiments, the sealing rings 182can be positioned at offset locations in adjacent ports 184 as shown inFIG. 7B. Given that the tube sizes in portable oxygen concentrators tendto be on the order of 1 cm in diameter or less, it can be important tokeep the density of ports 184 in multi-port interconnect 181 high, forexample, so that a multi-port interconnect 181 in the form of a blocksuch as shown in FIG. 7C can make multiple connections between ports 184and tubes 180 in a space just a few cm in dimension.

Alternatively, in some embodiments, as shown in FIGS. 7D and 7E, thesame or a similar effect can be achieved by use of a non-elastomericmember 183. In some embodiments, a non-elastomeric member 183 canuniformly compress the seal of multiple ports 184 in a single body inthe elastomeric element 181. By utilizing a non-compliant ornon-elastomeric member 183 that is assembled onto or manufactured intothe elastomer 181, uniform compression can be achieved on multipleinterconnect ports 184. The addition of the non-compliant member 183 canalso allow the use of secondary mounting features such as snap fits,screw bosses, hooks, or simple bosses to maintain the position of themating parts under pressure. This allows the single member 183 toprovide both a pneumatic connection and mechanical position connectionin a single component. In some embodiments, the combinationelastomeric/non-elastomeric arrangement shown in FIG. 7E can alsoincorporate sealing ring structures, such as sealing rings 182. Theintegrally formed multi-port block designs shown in FIGS. 7A-E canprovide the sealing and mechanical retention required in a portableoxygen concentrator, but still allow for removal, for repair, orservice. In contrast, barb designs employed in other oxygenconcentrators can prevent removal of tubes without damage to the tube,barb, or both. In some embodiments, the interconnects 181 shown in FIGS.7A-E can form a secure connection without requiring secondary retainerssuch as zip ties or clamps on each individual tube 180. Theinterconnects 181 can retain many tubes 180 and connections with greatlyfewer secondary mounting features than in single port interconnects.

FIGS. 7F and 7G depict an embodiment of an elastomeric multi-portinterconnection implementation 181 with four ports and sealing rings182. As shown in FIGS. 7H and 71, in some embodiments, twonon-elastomeric pieces are molded as described above to form aninterconnection element have a compliant interconnect 181 andnon-elastomeric pieces 183. In some embodiments, adding non-elastomericpieces 183 to a compliant interconnect 181 to form an assembly can allowfor the use of mounting elements, such as fastener holes, in a morerigid medium than an elastomeric interconnect alone, thus forming aninterconnection assembly offering both elastomeric isolation along withsecure mechanical mounting. Interconnection assembly elements 181 and183 may be joined in a variety of ways, including over molding theelastomeric piece to the hard plastic pieces when the elastomeric pieceis formed, assembling the components together with mechanical matingfeatures, or bonding the elastomeric piece to the hard plastic pieces.

FIGS. 7J and 7K show interconnection assemblies have elements 181 and183 mating with two sets of tubes—tubes 180 a from a valve assembly andtubes 180 b from a manifold assembly. When assembled together, themulti-port interconnect assembly having element 181 and 183 providescompact multiple gas connections in a small footprint, allows forelastomeric isolation between the two assemblies, and is easy toassemble.

As has been described in co-pending U.S. patent application Ser. Nos.15/608,775 and 15/027,948, the mounting of a compressor or compressorassembly in a portable oxygen concentrator can requires the use ofmate-able gas transport compliant members to accommodate the vibrationlevels of the compressors, as well as to dampen sound and vibration. Inthe case of mounts on the intake of the compressor, these memberstypically include circular tube connections and can be by necessity thinand flexible to maintain vibration isolation at low frequency rates of150 Hz or below. Such connections are reliable and functional and may befastened through the interior of the mount utilizing a screw or retainerwith a hole through it for air intake into the compressor. However,during assembly, these round tube connections can allow for theconnections to rotate due to the torque of the fastener, complicatingthe assembly process and introducing variability into the finalassembled configuration. In the case of output of the compressor,compliant members may also twist or be incorrectly aligned duringinstallation, also introducing assembly variation.

An improved arrangement is shown in FIGS. 8A-C. Compressor assembly 190includes a first compressor chamber 172 a having a first connector 191 aand a second compressor chamber 172 b having a connector 191 b. Thecompressor assembly 190 further includes tube 192. The tube 192 includesa first end having a first connection interface 173 a configured tocouple to the first connector 191 a to form a first interconnect. Thecompliant member 192 includes a second end having a second connectioninterface 173 b configured to couple to the second connector 191 b toform a second interconnect. A connection between the first connectioninterface 173 a to the first connector 191 a and the second connectioninterface 173 b to the second connector 191 b forms a gas connectionbetween the first compressor chamber 172 a and the second compressorchamber 172 b.

In some embodiments, one or more of the first connector 191 a, thesecond connector 191 b, and the tube 192 can be compliant. Utilizationof at least one compliant component can facilitate ease of connectionbetween the tube 192 and both the first connector 191 a and 191 b.

The first connection interface 173 a can be shaped, dimensioned, and/orotherwise configured to maintain the first interconnect in a fixedorientation. The second connection interface 173 b can be shaped,dimensioned, and/or otherwise configured to maintain the secondinterconnect in a fixed orientation.

In some embodiments, the first connector 191 a can have a shape thatmatches the shape of the first connection interface 173 a. In someembodiments, the first connection interface 173 a and the firstconnector 191 a can be shaped such that the first connection interface173 a and the first connector 191 a can mate in only one possibleorientation. In some embodiments, the first connection interface 173 aand the first connector 191 a can be shaped such that the firstconnection interface 173 a and the first connector 191 a are preventedfrom rotating when mated. In some embodiments, the first connectioninterface 173 a and the first connector 19 a can be square, generallysquare, or any other suitable shape. In some embodiments, the secondconnector 191 b can have a shape that matches the shape of the secondconnection interface 173 b. In some embodiments, the second connectioninterface 173 b and the second connector 191 b can be shaped such thatthe second connection interface 173 b and the second connector 191 b canmate in only one possible orientation. In some embodiments, the secondconnection interface 173 b and the second connector 191 b can be shapedsuch that the second connection interface 173 b and the second connector191 b are prevented from rotating when mated. In some embodiments, thesecond connection interface 173 b and the second connector 191 b can besquare, generally square, or any other suitable shape.

In some embodiments, one or both of the first connector 191 a and thesecond connector 191 b can be in the form of protrusions. In someembodiments, one or both of the first connection interface 173 a and thesecond connection interface 173 b can be in the form of receptacles.Alternatively, in some embodiments, one or both of the first connector191 a and the second connector 191 b can be in the form of receptacles,and one or both of the first connection interface 173 a and the secondconnection interface 173 b can be in the form of protrusions.

In some embodiments, a sealing element 189 can extend from each of theconnectors 191 a and 191 b and into the tube 192 when the connectors 191a and 191 b are coupled thereto. Each of the sealing elements 189 can beconfigured to form a seal with a complementary sealing element 194positioned within an interior of the tube 192. Alternatively, in someembodiments, sealing elements 194 can extend from the tube 192 into thefirst connectors 191 a and 191 b to mate with complementary sealingelements 189 within the connectors 191 a and 191 b.

Mount 193 illustrates another type of clocking. The mount 193 includes abase 193 a and one or more connectors 193 b. Each of the connectors 193b can include a compliant member 174. Each of the connectors 193 b canfurther include one or more protruding tabs 176 extending from thecompliant member 174. In some embodiments, each of the connectors 193 bcan include a pair of protruding tabs 176. In some embodiments, the pairof protruding tabs 176 can be spaced 180 degrees apart from one anotherabout a circumference of the compliant member 174. In some embodiments,the one or more protruding tabs 176 can be configured to couple with oneor more complementary slots 177 on the compressor 190 configured toreceive the pair of protruding tabs 176. In some embodiments, thecoupling between the protruding tabs 176 and the slots 177 can clock theinterconnect in a fixed orientation. Other tab/slot or post/holearrangements may also be used. For example, in some embodiments, themount 193 includes slots configured to receive protruding tabs from thecompressor assembly 190.

In some embodiments, the protruding tabs 176 can be formed of adifferent material than the compliant member 174. In some embodiments,as shown in FIG. 8C, the protruding tabs 176 can be part of a separateclocking member or insert 195, which can be formed of a rigid material,such as metal or plastic. The insert 195 can adds rigidity to theclocking connection. In some embodiments, the compliant member 174 andthe clocking member 195 may be attached during a molding process, joinedwith adhesives, or clamped together. In some embodiments, the base 193 amay also be separately manufactured. In some embodiments, the base 193 acan be formed of a rigid material such as metal or plastic. The base 193a can add rigidity to the clocking connection.

In some embodiments, the mount 193 can be coupled to the compressorassembly 190 by a hollow screw. In some embodiments, intake air can bedrawn through the hollow screw.

In some embodiments, the inclusion of clocking arrangements forcompliant member interconnects improves the manufacturing of theportable oxygen concentrator. In the absence of clocking members,compliant member 193 may twist during installation, which can lead totearing of the material or the compressor assembly being held out ofplace by the twisting of the mount.

Portable oxygen concentrators can require compact O₂ sensors to monitorthe oxygen content of the gas delivered to patients. Such sensors can bedifficult to find commercially in the size range and price pointsrequired for portable oxygen concentrators. Accordingly, many commercialportable concentrators have custom designed oxygen sensors. Thesesensors generally rely on the fact that the speed of sound in a gas isdependent on the gas composition and therefore oxygen concentration canbe inferred from the speed of sound.

Examples of oxygen sensor designs for the oxygen concentrators are shownin FIGS. 9A and 9B. A sound emitter 201 is mounted to one end of tube200, and a sound receiver 202 is mounted to the other end of the tube100. In principle, a measurement can be performed based on the speed ofsound (approximately 350 m/s), a length of the tube, and a transit timebetween the emitter 201 and the receiver 202. In practice, pressure andtemperature variations affect signal reception rise time, and standingwave propagation may induce distortions that make the actual use of sucha sensor problematic, and significant design and implementation issuesaffect this type of design. In addition, commercially availabletransducers are available in limited packaging options, potentiallymaking the inclusion of such a sensor into the concentrator laborintensive.

An alternative embodiment of an oxygen sensor 210 is shown in FIGS. 9Cand 9D. The oxygen sensor 210 includes an emitter 201 comprising anactive surface 211 configured to emit an acoustic signal. The oxygensensor 210 includes a receiver 202 having an active surface 212configured to receive an acoustic signal. The oxygen sensor 210 furtherincludes a body 215 forming a chamber 205. The body 215 includes a firstopening 216 configured to receive the emitter 201 such that the activesurface 211 of the emitter 201 is exposed to the chamber 205. The body215 includes a second opening 217 configured to receive the receiver 202such that the active surface 212 of the receiver 202 is exposed to thechamber 205.

In some embodiments, body 215 can include one or more reflectors 218configured to reflect an acoustic signal so as to establish an acousticpath between the active surface 211 of the emitter 201 and the activesurface 212 of the receiver 202. In some embodiments, the body 215 caninclude at least two reflectors 218. In some embodiments, the reflectors218 can be formed by or positioned on two angled opposing faces withinthe body 215. An example of an acoustic path 206 is shown in FIG. 9D.Alternative arrangements may include an acoustic path with onereflection or multiple reflections.

In some embodiments, the first opening 216 and the second opening 217can be coplanar. In some embodiments, the first opening 216 and thesecond opening 217 can be positioned in parallel to one another. In someembodiments, the active surface 211 of the emitter 201 and the activesurface 212 of the receiver 202 can be coplanar. In some embodiments,the emitter 201 and receiver 202 are mounted with their active surfaces211 and 212 in the same orientation, for example, parallel with oneanother. In some embodiments, the active surface 211 of the emitter 201and the active surface 212 of the receiver 202 are oriented to face inparallel directions.

In some embodiments, the oxygen sensor 210 further includes one or moreseals 204. The seals 204 can be in the form of sealing rings. In someembodiments, the seals 204 can include a first seal 204 configured toprovide a seal between the first opening 216 and the emitter 201 and asecond seal 204 configured to provide a seal between the second opening217 and the receiver 202.

In some embodiments, the sensor 210 can include a printed circuit board203. In some embodiments, the emitter 201 and receiver and 202 can beco-mounted to the printed circuit board 203. In some embodiments, one ormore additional sensors, such as a temperature sensor 219 a and/or apressure sensor 219 b as shown in FIGS. 9D, 9E, and 9F, may beco-mounted to the PCB 203. In some embodiments, the body 215 may mountdirectly to the PCB 203. In some embodiments the body 215 and seals 204can mount directly to the PCB.

In some embodiments, the temperature sensor 219 a can be configured tomeasure a temperature of oxygen gas within the chamber 205. In someembodiments, the temperature sensor 219 a can be configured to measure atemperature of air outside the chamber 205.

In some embodiments, the pressure sensor 219 b can be configured tomeasure a pressure of oxygen gas within the chamber 205. In someembodiments, the pressure sensor 219 b can be configured to measure thepressure of air outside the chamber 205.

In some embodiments, the sound path 206 within the chamber 205 may beconfigured to reduce standing wave propagation, eliminating or at leastreducing one of the difficult to characterize behaviors of the tube typesensors shown in FIGS. 9A-B.

Many portable oxygen concentrators provide two or more output flowsettings, thereby allowing a single model concentrator to address arange of patient oxygen needs. In some embodiments, it may be desirablefor the compressor for such concentrators to be designed with a maximumflow setting driving the intended compressor capacity. However, it isoften the case that most users will operate a given concentrator modelat a flow setting lower than maximum flow during use of the oxygenconcentrator. In some instances, a user will operate the oxygenconcentrator at a number of different settings during use. In someinstances, a user will operate the oxygen concentrator at a settinglower than the maximum flow setting during a majority of the duration ofuse of the concentrator. Thus, even though a compressor motor must becapable of operating at the maximum flow setting, the highest flowsetting may not be used often. Accordingly, it may be advantageous totune the motor and motor control function to improve efficiency at themost commonly used flow settings while maintaining the ability tooperate across the full range of flow settings.

Referring to FIG. 10A, a simplified illustration of a control system 188for controlling a motor 199 of the compressor 190 is shown. The controlsystem 188 includes a power source 198, a voltage controller 196, and apulse width modulation (PWM) controller 197. In some embodiments, thevoltage controller 196 and PWM controller 197 can be combined into asingle motor controller or, alternatively, may be separate elements.

In some embodiments, the power source 198 provides a power sourcevoltage. In some embodiments, the power source 188 provides a DC powersource voltage. In some embodiments, the power source is a battery, anAC to DC power supply, a fixed power source having car DC power ports,or any other suitable power source.

In some embodiments, one or both of the voltage controller 196 and thePWM controller 197 can drive operation of the compressor 190, forexample, by providing compressor motor control signals. In someembodiments, the voltage controller 196 is configured to selectivelymodify the power source voltage to provide a plurality of supplyvoltages. In some embodiments, the voltage controller 196 is configuredto modify the power source voltage to provide one or more supplyvoltages higher than the power source voltage.

In some embodiments, the pulse width modulation controller 197 isconfigured to selectively apply pulse width modulation to supplyvoltages at plurality of pulse width modulation duty cycles. In someembodiments, one or both of the voltage controller 196 and PWMcontroller 197 can be used to provide a plurality of motor controlsignals to the motor 199.

In some embodiments, for example, when the power source 188 is abattery, the method for operating the compressor 190 further includesdynamically monitoring the power source voltage and adjusting one orboth of the supply voltage and the pulse width modulation duty cycle toaccommodate power source voltage changes to achieve a desired efficiencyof the compressor.

FIGS. 10B-C show examples of oxygen concentrator voltages over time.Many oxygen concentrators operate in a manner illustrated in FIG. 10C. Anominal voltage is supplied from a power source, and the motor speed andtherefore compressor output is controlled by applying PWM control to thenominal voltage, varying the motor speed by changing the duty cycle ofthe PWM supply signal. Thus, a low duty cycle is applied for the lowestsettings varying up to a very high duty cycle or even a non-modulated DCsignal for the highest settings.

However, the voltage level of the nominal voltage also has an effect ofcompressor efficiency. For example, switching losses when PWM is appliedmay be lower if the voltage level is lower. Losses may be minimized bymodulating the nominal voltage, for example, using a voltage controller196, and keeping the PWM duty cycle near 100%, or, alternatively at ornear a certain target threshold. Additionally, the efficiency curve of agiven compressor motor can roll off at higher torques at a given speedfor a certain supply voltage. In general, the efficiency of a compressormotor and controller operation has been found to be a function of bothPWM duty cycle and voltage supply level. It is possible to measure, e.g.calibrate, motor efficiency over a range of supply voltage/PWM dutycycle combinations to optimize battery lifetime for each combination.

Battery lifetime naturally varies significantly with concentrator outputflow. For one concentrator design produced by the applicant of thecurrent disclosure, with six settings, the most common setting used bypatients is the second from the lowest setting. At this setting, theconcentrator may have several hours of battery life, for example 10hours. At the highest flow setting, the concentrator may have one hourof use time. Therefore, an adjustment of efficiency that say adds 10% tothe most used setting will add a full hour of use time. If theimprovement in efficiency at the most common setting results in a 10%loss at the high setting, that penalty is only six minutes. It istherefore advantageous to tune the compressor motor control to achievehigher efficiency at the commonly used lower settings, and this tuningcan be improved by varying the supply voltage as well as the PWM dutycycle, for example, by the voltage controller 196 and PWM controller 197as described above.

Accordingly, a method of operating an oxygen concentrator can includemodifying the power source voltage using the voltage controller 196 andthe PWM controller 197. A concentrator design can be calibrated over arange of supply voltages and PWM duty cycles, possibly with the maximumsetting representing a very high duty cycle and/or the highestachievable voltage.

For some concentrator designs, efficiencies as a function of supplyvoltage/PWM duty cycle may be calculated, modeled, or measured. Somecombination of techniques may be used. In some embodiments, a nominalvoltage may be supplied which may be increased or decreasedconcurrently, for example, by the voltage controller 196, with PWMcontrol, for example, by the PWM controller 197, to achieve efficiencytargets at each flow setting. The use of a supply voltage controller 196in addition to the PWM controller 197 may result in a decreasedcompressor-motor-controller efficiency at certain operational points dueto the operation of these electronics, but an optimum configuration canbe found that results in minimal losses at a desired design point. Theselosses may then be less than losses encountered from a PWM only controlbased system, resulting in a higher overall system efficiency. Forexample, in some embodiments, switching losses may be reduced. In FIGS.10B-D, a nominal voltage and a PWM rate that is selected fromcalibration data that achieves desirable efficiency at a most commonsetting is supplied. FIGS. 10C and 10D show similar amounts of effectivevoltage being applied to the motor for different amounts of appliedvoltage and PWM duty cycle applied. For the less common settings, acombination of increasing or decreasing supply voltage and changing PWMduty cycle is applied. Of course, other combinations may be used aswell, such as providing a DC voltage configured for the highest setting,and lowering the voltage and changing PWM for each lower setting.However, when the nominal settings are picked, the result is that bothsupply voltage and PWM duty cycle are varied to selectively increaseefficiency at desired flow settings. This can be illustrated in thesurface plot in FIGS. 10E and 10F, which show how the effective motorvoltage is a function of a combination of both applied voltage and thePWM duty cycle. The intersection of a given horizontal plane with thesurface plot exemplifies the available combination of PWM and appliedvoltage that results in the same effective motor voltage along theintersecting line. Along this line is a maximum efficiency point thatcan be measured or calculated.

Battery-operated devices can have various supply voltages, such as froma car or an AC to DC power supply, as well as various voltages dependingupon the state of charge or depletion of the battery. It is possible tomonitor the dynamically changing battery voltage and accordingly modifythe PWM duty cycle and voltage to the controller dynamically to maximizesystem efficiency. It is also possible to increase the supply voltagerelative to battery voltage on some higher flow settings to achievedesired motor performance while letting the voltage available from thebattery to pass through and utilize only PWM control on other flowsettings.

In some embodiments, a method for operating a compressor assembly 190includes determining an efficiency of the compressor assembly 190.Determining the efficiency of the compressor assembly 190 can includemeasuring, calibrating, calculating, or modeling motor efficiency of themotor 199 over a range of supply voltage and pulse width modulation dutycycle combinations. Each combination can include a supply voltage fromthe voltage controller 196 and a pulse width modulation duty cycle fromthe pulse width modulation controller 197.

In some embodiments, the method for operating the compressor assembly190 can include selecting a supply voltage and a pulse width modulationduty cycle for use at at least one output flow setting based on thedetermined efficiency of the compressor assembly 190.

In some embodiments, the method for operating the compressor 190assembly 190 can include generating the selected supply voltage bymaintaining, reducing, or increasing a nominal supply voltage, forexample, using the voltage controller 196. In some embodiments, thenominal supply voltage is a desired voltage for one of the plurality ofoutput flow settings. In some embodiments, the nominal supply voltage isa desired supply voltage for a maximum output flow setting. In someembodiments, the nominal supply voltage is used without pulse widthmodulation as the motor control signal for a highest output flow settingof the plurality of outflow settings of the compressor assembly 190. Insome embodiments, a combination of supply voltage regulation, forexample, using the voltage controller 196, and pulse width modulation,for example, using the PWM controller 197, are applied to the nominalsupply voltage to provide motor control signals to the motor 199 for oneor more output flow settings lower than the highest output flow settingof the compressor assembly 190.

In some embodiments, the selected supply voltage and the selected pulsewidth modulation duty cycle are selected to optimize efficiency at amost commonly used output flow setting of the plurality of output flowsettings while maintaining the ability to operate at each of theplurality of output flow settings.

In some embodiments, the selected supply voltage and the selected pulsewidth modulation duty cycle are selected to reduce switching losses atat least one output flow setting of the plurality of output flowsettings.

In some embodiments, the method for operating the compressor 190 caninclude applying the selected pulse width modulating duty cycle.

In addition to having multiple flow settings, the nature of a swingadsorption system results in a head profile that changes dynamicallyover the course of a pressure, pressure-vacuum, or vacuum swing cycle.The amount that the load on the compressor motor and control electronicsvaries over the course of a cycle depends on the number of valvesutilized, number of beds used, product gas tank used, and sequencing andtiming (e.g. specific PSA cycle employed) and can thus vary from ˜0-30psi. It is therefore advantageous to modulate the controller voltage andPWM duty cycle dynamically to optimize efficiency over the course of aPSA cycle. This can be performed in real-time using current, power, orpressure measurements, a feed-forward method using any of theaforementioned, any combination of them, or other techniques.

In some embodiments, in which the compressor is part of a swingadsorption system, the method for operating the compressor 190 caninclude monitoring a pressure profile over the course of a pressureswing adsorption cycle, a pressure-vacuum swing adsorption cycle, or avacuum swing adsorption cycle. In some embodiments, the method caninclude dynamically adjusting the supply voltage and pulse widthmodulation duty cycle to improve efficiency over the course of thepressure swing adsorption cycle, the pressure-vacuum swing adsorptioncycle, or the vacuum swing adsorption cycle. In some embodiments,monitoring the head profile and adjusting the supply voltage and pulsewidth modulation duty cycle are performed during the pressure swingadsorption cycle, the pressure-vacuum swing adsorption cycle, or thevacuum swing adsorption cycle. In some embodiments, monitoring the headprofile includes monitoring one or more of current measurements, powermeasurements, and pressure measurements through a feed forward process.

The embodiments described herein are exemplary. Modifications,rearrangements, substitute processes, alternative elements, etc. may bemade to these embodiments and still be encompassed within the teachingsset forth herein. One or more of the processes described herein may becarried out by one or more processing and/or digital devices, suitablyprogrammed.

The various illustrative processing, data display, and user interfacesdescribed in connection with the embodiments disclosed herein can beimplemented as electronic hardware, computer software, or combinationsof both. To clearly illustrate this interchangeability of hardware andsoftware, various illustrative components, blocks, and modules have beendescribed above generally in terms of their functionality. Whether suchfunctionality is implemented as hardware or software depends upon theparticular application and design constraints imposed on the overallsystem. The described functionality can be implemented in varying waysfor each particular application, but such implementation decisionsshould not be interpreted as causing a departure from the scope of thedisclosure.

The various illustrative logical blocks and modules described inconnection with the embodiments disclosed herein can be implemented orperformed by a machine, such as a processor configured with specificinstructions, a digital signal processor (DSP), an application specificintegrated circuit (ASIC), a field programmable gate array (FPGA) orother programmable logic device, discrete gate or transistor logic,discrete hardware components, or any combination thereof designed toperform the functions described herein. A processor can be amicroprocessor, but in the alternative, the processor can be acontroller, microcontroller, or state machine, combinations of the same,or the like. A processor can also be implemented as a combination ofcomputing devices, e.g., a combination of a DSP and a microprocessor, aplurality of microprocessors, one or more microprocessors in conjunctionwith a DSP core, or any other such configuration.

The elements of the embodiments disclosed herein can be embodieddirectly in hardware, in a software module executed by a processor, orin a combination of the two. A software module can reside in RAM memory,flash memory, ROM memory, EPROM memory, EEPROM memory, registers, harddisk, a removable disk, a CD-ROM, or any other form of computer-readablestorage medium known in the art. An exemplary storage medium can becoupled to the processor such that the processor can read informationfrom, and write information to, the storage medium. In the alternative,the storage medium can be integral to the processor. The processor andthe storage medium can reside in an ASIC. A software module can comprisecomputer-executable instructions which cause a hardware processor toexecute the computer-executable instructions.

Conditional language used herein, such as, among others, “can,” “might,”“may,” “e.g.,” and the like, unless specifically stated otherwise, orotherwise understood within the context as used, is generally intendedto convey that certain embodiments include, while other embodiments donot include, certain features, elements, and/or states. Thus, suchconditional language is not generally intended to imply that features,elements and/or states are in any way required for one or moreembodiments or that one or more embodiments necessarily include logicfor deciding, with or without author input or prompting, whether thesefeatures, elements and/or states are included or are to be performed inany particular embodiment. The terms “comprising,” “including,”“having,” “involving,” and the like are synonymous and are usedinclusively, in an open-ended fashion, and do not exclude additionalelements, features, acts, operations, and so forth. Also, the term “or”is used in its inclusive sense (and not in its exclusive sense) so thatwhen used, for example, to connect a list of elements, the term “or”means one, some, or all of the elements in the list.

Disjunctive language such as the phrase “at least one of X, Y or Z,”unless specifically stated otherwise, is otherwise understood with thecontext as used in general to present that an item, term, etc., may beeither X, Y or Z, or any combination thereof (e.g., X, Y and/or Z).Thus, such disjunctive language is not generally intended to, and shouldnot, imply that certain embodiments require at least one of X, at leastone of Y or at least one of Z to each be present.

Unless otherwise explicitly stated, articles such as “a” or “an” shouldgenerally be interpreted to include one or more described items.Accordingly, phrases such as “a device configured to” are intended toinclude one or more recited devices. Such one or more recited devicescan also be collectively configured to carry out the stated recitations.For example, “a processor configured to carry out recitations A, B andC” can include a first processor configured to carry out recitation Aworking in conjunction with a second processor configured to carry outrecitations B and C.

While the above detailed description has shown, described, and pointedout novel features as applied to illustrative embodiments, it will beunderstood that various omissions, substitutions, and changes in theform and details of the devices illustrated can be made withoutdeparting from the spirit of the disclosure. As will be recognized,certain embodiments described herein can be embodied within a form thatdoes not provide all of the features and benefits set forth herein, assome features can be used or practiced separately from others. Allchanges which come within the meaning and range of equivalency of theclaims are to be embraced within their scope.

What is claimed is:
 1. A compressor assembly for a portable oxygenconcentrator, comprising: a first compressor chamber comprising a firstconnector; a second compressor chamber comprising a second connector;and a tube comprising a first end comprising a first connectioninterface configured to connect to the first connector and a second endcomprising a second connection interface configured to connect to thesecond connector; wherein the first connection interface is shaped tomaintain the connection between the first connector and the firstconnection interface in a fixed orientation and the second connectioninterface is shaped to maintain the connection between the secondconnector and the second connection interface in a fixed orientation;and wherein one or more of the first connector, the second connector,and the tube are compliant.
 2. The compressor assembly of claim 1,wherein the first connector has a shape and the first connectioninterface of the tube has a shape that matches the shape of the firstconnector, and wherein the second connector has a shape and the secondconnection interface has a shape that matches the shape of the secondconnector.
 3. The compressor assembly of claim 2, wherein the shapes ofthe first connection interface, the second connection interface, thefirst connector, and the second connector are square.
 4. A compressorassembly for a portable oxygen concentrator, comprising: a compliantmount comprising at least one connector, the at least one connectorcomprising: a compliant member; and a pair of protruding tabs extendingfrom the compliant member; and a compressor comprising: a firstcompressor chamber; a second compressor chamber; and at least one pairof slots, the at least one pair of slots configured to receive the pairof protruding tabs of the at least one connector.
 5. The compressorassembly of claim 4, wherein the protruding tabs are spaced 180° apartfrom one another around a circumference of the compliant member.
 6. Thecompressor assembly of claim 4, wherein the pair of protruding tabs areformed of a different material than the compliant member.
 7. Thecompressor assembly of claim 4, wherein the at least one connectorcomprises two connectors.
 8. A sensor assembly, comprising: an oxygensensor, comprising: at least one emitter comprising an active surfaceconfigured to emit an acoustic signal; at least one receiver comprisingan active surface configured to receive the acoustic signal; and a bodyforming a chamber, the body comprising: a first opening configured toreceive the at least one emitter such that the active surface of the atleast one emitter is exposed to the chamber; a second opening configuredto receive the at least one receiver such that the active surface of theat least one receiver is exposed to the chamber; and at least tworeflectors configured to reflect the acoustic signal so as to establishan acoustic path between the active surface of the emitter and theactive surface of the receiver.
 9. The sensor assembly of claim 8,wherein the first opening and the second opening are coplanar.
 10. Thesensor assembly of claim 8, wherein the active surface of the emitterand the active surface of the receiver are coplanar.
 11. The sensorassembly of claim 8, wherein the active surface of the emitter and theactive surface of the receiver are oriented to face in paralleldirections.
 12. The sensor assembly of claim 8, wherein the oxygensensor further comprises one or more sealing rings configured to providea seal between the first opening and the emitter and the second openingand the receiver.
 13. The sensor assembly of claim 8, further comprisinga printed circuit board, wherein the emitter and receiver are mounted tothe printed circuit board, and wherein the printed circuit board ismounted to the body.
 14. The sensor assembly of claim 8, wherein theoxygen sensor comprises a temperature sensor configured to measure atemperature of oxygen gas within the chamber.
 15. The sensor assembly ofclaim 8, wherein the oxygen sensor comprises a temperature sensorconfigured to measure a temperature of air outside the chamber.
 16. Thesensor assembly of claim 8, wherein the oxygen sensor comprises apressure sensor configured to measure a pressure of oxygen gas withinthe chamber.
 17. The sensor assembly of claim 8, wherein the oxygensensor comprises a pressure sensor configured to measure a pressure ofair outside the chamber.
 18. The sensor assembly of claim 8, furthercomprising a breath detection sensor.